EP4178683A1 - Appareil de protection contre les chutes avec dispositif de freinage comprenant un cliquet porté en flexion et un contrefort monté sur tambour - Google Patents

Appareil de protection contre les chutes avec dispositif de freinage comprenant un cliquet porté en flexion et un contrefort monté sur tambour

Info

Publication number
EP4178683A1
EP4178683A1 EP21838098.8A EP21838098A EP4178683A1 EP 4178683 A1 EP4178683 A1 EP 4178683A1 EP 21838098 A EP21838098 A EP 21838098A EP 4178683 A1 EP4178683 A1 EP 4178683A1
Authority
EP
European Patent Office
Prior art keywords
pawl
drum
support plate
flexure
ratchet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21838098.8A
Other languages
German (de)
English (en)
Other versions
EP4178683A4 (fr
Inventor
Greg E. Schrank
Daniel C. LEWIS
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of EP4178683A1 publication Critical patent/EP4178683A1/fr
Publication of EP4178683A4 publication Critical patent/EP4178683A4/fr
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D59/00—Self-acting brakes, e.g. coming into operation at a predetermined speed
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
    • A62B35/00—Safety belts or body harnesses; Similar equipment for limiting displacement of the human body, especially in case of sudden changes of motion
    • A62B35/0093—Fall arrest reel devices
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
    • A62B35/00—Safety belts or body harnesses; Similar equipment for limiting displacement of the human body, especially in case of sudden changes of motion
    • A62B35/04—Safety belts or body harnesses; Similar equipment for limiting displacement of the human body, especially in case of sudden changes of motion incorporating energy absorbing means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D63/00—Brakes not otherwise provided for; Brakes combining more than one of the types of groups F16D49/00 - F16D61/00
    • F16D63/006—Positive locking brakes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/14—Mechanical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2127/00—Auxiliary mechanisms
    • F16D2127/001—Auxiliary mechanisms for automatic or self-acting brake operation
    • F16D2127/002—Auxiliary mechanisms for automatic or self-acting brake operation speed-responsive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2127/00—Auxiliary mechanisms
    • F16D2127/02—Release mechanisms

Definitions

  • Fall-protection apparatus such as self-retracting lifelines have often found use in applications such as building construction and the like.
  • a fall-protection apparatus comprising a rotationally- activated braking device that comprises at least one pawl that is a flexure-borne pawl, and that further comprises at least one buttress that is affixed to a sidewall of rotatable drum of the braking device.
  • a flexure-borne pawl may be a velocity-actuated pawl and/or it may be an acceleration-actuated pawl.
  • Fig. 1 is a perspective view of an exemplary fall-protection apparatus.
  • Fig. 2 is a perspective partially-exploded view of various components of an exemplary fall- protection apparatus.
  • Fig. 3 is an isolated perspective exploded view of particular components of an exemplary fall- protection apparatus.
  • Fig. 4 is a plan view of an exemplary arrangement of flexure-borne pawls
  • Fig. 5 is a plan view of another exemplary arrangement of flexure-borne pawls.
  • Fig. 6 is a perspective view of another exemplary arrangement of flexure-bome pawls.
  • Fig. 7 is a plan view of the exemplary arrangement of pawls of Fig. 6.
  • Fig. 8 is an isolated perspective view of various components of another exemplary fall -protection apparatus.
  • Fig. 9 is a partially exploded view of the components of Fig. 8.
  • Fig. 10 is an exploded view of some components of Fig. 9.
  • Fig. 11 is a plan view of another exemplary arrangement of flexure-bome pawls.
  • Fig. 12 is a plan view of another exemplary arrangement of flexure-bome pawls.
  • Fig. 13 is a perspective exploded view of an exemplary friction brake.
  • Fig. 14 is a perspective exploded view of various components of another exemplary fall-protection apparatus.
  • Fig. 15 is an unexploded perspective view of various components of Fig. 14.
  • Fig . 16 is a perspective view of vanous components of another exemplary fall -protection apparatus .
  • Fig. 17 is a perspective exploded view of various components of Fig. 16.
  • Like reference numbers in the various figures indicate like elements. Some elements may be present in identical or equivalent multiples; in such cases only one or more representative elements may be designated by a reference number but it will be understood that such reference numbers apply to all such identical elements.
  • all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.
  • terms such as “first” and “second” may be used in this disclosure, it should be understood that those terms are used in their relative sense only unless otherwise noted.
  • Geometric descriptors are used herein, unless otherwise specified, with reference to a drum 80 and an associated pawl-support plate 40 of a fall-protection apparatus as described in detail herein and as shown in Fig. 2.
  • the term “axially” refers to a direction at least generally parallel to the axis of rotation of the drum, plate, and associated components (e.g. axis of rotation 81 as shown in Figs. 2 and 8).
  • radial and like terms refers to a direction generally parallel to the radius and diameter of the drum and plate and generally perpendicular to the axial direction.
  • circumferential refers to an arcuate direction that exhibits a generally constant radius relative to the axis of rotation of the drum and associated components (for example, orbital pathway 25 as indicated on Fig. 4, follows a circumferential path).
  • Leading refers to a component that, upon such rotation, passes a fixed point before a “trailing” component passes the fixed point.
  • end 22 of pawl 20 as shown in Fig. 4 is a leading end; end 23 is a trailing end of pawl 20.
  • a “leading” direction and a “trailing” direction may be respectively referred to herein as a circumferentially-forward direction and a circumferentially-rearward direction.
  • the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring a high degree of approximation (e.g., within +/- 20 % for quantifiable properties).
  • the term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/- 10% for quantifiable properties).
  • the term “essentially” means to a very high degree of approximation (e.g., within plus or minus 2 % for quantifiable properties; it will be understood that the phrase “at least essentially” subsumes the specific case of an “exact” match.
  • a fall-protection apparatus by which is meant an apparatus that acts to controllably decelerate a human user of the apparatus in the event of a user fall.
  • a fall- protection apparatus is a non-motorized apparatus.
  • a safety line of the apparatus is not moved (i.e., extended or retracted from a housing of the apparatus) by way of an electrically powered motor; in other words, the apparatus is not used as part of a system (e.g., an elevator, a hoist, etc.) that uses one or more motors to raise or lower a load.
  • such a fall-protection apparatus may be a self-retracting lifeline (SRL); i.e., a deceleration apparatus comprising a housing at least partially contains a drum-wound safety line that can be extended from the housing and retracted into the housing under slight tension during normal movement of a human user of the apparatus, and which, upon the onset of a user fall, automatically arrests (i.e., slows to a controlled rate, or completely stops) the fall of the user.
  • SRL self-retracting lifeline
  • a deceleration apparatus comprising a housing at least partially contains a drum-wound safety line that can be extended from the housing and retracted into the housing under slight tension during normal movement of a human user of the apparatus, and which, upon the onset of a user fall, automatically arrests (i.e., slows to a controlled rate, or completely stops) the fall of the user.
  • Such an apparatus may comprise a safety line (made e.g. of metal or any other
  • such an apparatus may comprise a drum that is rotatably mounted within a housing therein such that such that the safety line can be wound about the drum when the line is retracted into the housing.
  • a rotationally-activated braking device By this is meant a device that is configured to slow (e.g. stop) the rotation of the drum upon rotation of the drum with a velocity and/or acceleration or combination thereof, that is above a predetermined threshold value.
  • FIG. 1 An exemplary fall-protection apparatus (a self-retracting lifeline) 1 is depicted in Fig. 1.
  • Such an apparatus may comprise a housing 111 that is provided e.g. from a first housing piece 112 and second housing piece 113 that are assembled and fastened together to form the housing. Housing pieces 112 and 113 may be fastened together e.g. by bolts or by any other suitable fasteners.
  • Various ancillary components such as e.g.
  • housing 111 may be load-bearing; in some embodiments, a load bracket or similar component may be present and may provide at least a portion of the load-bearing path of the apparatus. Further details of exemplary apparatus 1 are depicted in Fig. 2, which is a partially exploded view with the second housing piece 113 omitted.
  • a dmm 80 which defines a receiving space 88 (indicated in Fig. 8) into which is wound (e.g., spiral- wound) a length of safety line 115 (with the term line broadly encompassing any elongate, windable load- bearing member, including e.g. webbing, cable, rope, etc., made of any suitable synthetic or natural polymeric material, metal, etc., or any combination thereof).
  • a proximal end of line 115 is connected, directly or indirectly, to drum 80 (such a connection encompasses configurations in which the proximal end of line 115 is connected to a shaft 82 on which drum 80 is mounted).
  • Drum 80 is rotatably mounted within housing 111, e.g. by being rotatably mounted on a shaft 82 and/or by being mounted on a shaft 82 that is rotatable relative to the housing.
  • a biasing member 86 (not visible in Fig. 2 but indicated in generic representation in Fig. 1, and which may be e.g. a suitable spring such as a spiral-coiled torsion spring) may be provided, which serves to bias the dmm toward rotating in a direction that will retract safety line 115 onto the dmm unless the biasing force is overcome e.g. by movement of a human user.
  • Apparatus 1 comprises a rotationally-activated braking device 10, as shown in exemplary embodiment in Fig. 2.
  • a rotationally-activated braking device relies on one or more pawls 20.
  • the at least one pawl 20 is co-rotatable with dmm 80.
  • the pawls are able to rotate along with dmm 80, with the pawl(s) moving in an orbital path about a center of orbital motion that coincides with the axis of rotation of the dmm.
  • such an arrangement is achieved by mounting pawl(s) 20 on a pawl-support plate 40 which is mounted on the same shaft 82 on which dmm 80 is mounted.
  • pawl -support plate 40 may be axially co-mounted with dmm 80 and may be co-rotatable with dmm 80.
  • a pawl-support plate may be fixed to (e.g. attached directly to) drum 80.
  • such an arrangement may be achieved e.g. by mounting pawl(s) directly on dmm 80, e.g. so that a side flange or wall of dmm 80 serves as a pawl-support plate.
  • pawl-support plate 40 will be in fixed relation with (i.e., will always rotate in unison with) dmm 80.
  • plate 40 will be configured so that it can rotate slightly relative to dmm 80 under some circumstances (e.g. upon exposure to sufficient acceleration in the event of a user fall). However, even in such embodiments, plate 40 will typically rotate in unison with drum 80 the vast majority of the time during ordinary use of apparatus 1.
  • the one or more pawls 20 are arranged (e.g. mounted on a pawl-support plate 40 as described in detail later herein) so that they can bodily move between a disengaged position and an engaged position.
  • the pawl(s) 20 are configured so that in ordinary use of the fall-protection apparatus, an engaging end 22 of a pawl 20 is maintained in a non-engaged position in which it does not engage with any component (e.g. a ratchet tooth) that would limit the rotation of the drum.
  • This arrangement allows the dmm to rotate freely back and forth thus allowing extension and retraction of the safety line in response to movements of a human user of the fall-protection apparatus as the user goes about their workplace activities.
  • At least one pawl 20 is motivated into an engaged position in which the engaging end 22 of the pawl 20 is able to physically contact a tooth of a ratchet to slow or stop the rotation of the dmm.
  • Exemplary ratchets 90 and teeth 91 thereof are depicted in exemplary embodiments in various Figures herein; however, it will be appreciated that many ratchet arrangements are possible, as is discussed in detail later herein.
  • a pawl will not “engage” with a ratchet tooth until its engaging end actually contacts the tooth.
  • a pawl will be considered to be in an engaged position upon the pawl having been actuated so that its engaging end is in a position (e.g. having moved radially outward) in which it will contact a ratchet tooth upon continued motion of the pawl along its orbital path.
  • pawls are depicted in an engaged position while others are depicted in a disengaged position.
  • a pawl that is in an engaged position is subscripted “e” (e.g. 20 e ). It will be appreciated that when the apparatus is in a non-fall situation (e.g. with the dmm rotating very slowly or not at all), all such pawls will typically be in a disengaged position (e.g. a “home” position as described later herein).
  • a rotationally-activated braking device in use of a rotationally-activated braking device as disclosed herein, engaging of at least one pawl with a tooth of a ratchet will at least slow, e.g. will arrest, the rotation of the dmm.
  • the rotationally-activated braking device may bring the dmm to a “hard stop” in which the rotation of the dmm ceases essentially at the instant that the pawl engages the tooth.
  • the safety line of such an apparatus may include a so-called shock absorber (e.g. a tear web or tear strip) to minimize the force experienced by a human user as the user is brought to a halt.
  • the term “hard stop” is used for convenience in distinguishing such a stop from a more gradual stop that relies on the use of a friction brake as described later herein; the term “hard stop” does not imply that the user is subjected to, e.g., excessively hard forces in being brought to a halt.)
  • the rotationally-activated braking device relies on a friction brake that, rather than bringing the dmm near-instantly to a “hard stop”, brings the drum to a halt in a more gradual manner as described in detail later herein. This can minimize the force experienced by a human user as a fall is being arrested, e.g. without requiring the presence of a shock absorber in the safety line.
  • an upper, anchorage end 108 of the apparatus may be connected (e.g. by way of connection feature 114) to a secure anchorage (fixed point) of a workplace stmcture (e.g., a girder, beam or the like).
  • the distal end of line 115 may then be attached (e.g., by way of hook 116) to a harness worn by a worker.
  • drum 80 rotates in a first direction (w) so that line 115 is extended (paid out) from within housing 111.
  • drum 80 rotates in a second, opposite direction (e.g.
  • pawl(s) 20 is maintained in a disengaged position in which an engaging end 22 of pawl 20 does not engage a tooth 91 of a ratchet 90 of the rotationally-activated braking device.
  • a leading/engaging end 22 of pawl 20 is caused to move to a position in which it can engage with a ratchet tooth 91 of a ratchet 90 (i.e., is actuated) by the arrangements disclosed herein, whereupon the falling of the worker is arrested as discussed in detail herein.
  • a fall-protection apparatus 1 comprises at least one flexure-borne pawl 20.
  • multiple such flexure-borne pawls 20 may be present and may be supported by a common pawl-support plate 40, as discussed later herein (noting that in some embodiments a sidewall or flange of drum 80 may serve as a pawl-support plate rather than a separate pawl-support plate 40 being used in the manner of Fig. 2).
  • three such flexure-borne pawls 20 may be provided, as shown in exemplary embodiment in Figs. 2-5 herein.
  • Such pawls may be e.g. circumferentially spaced along a circular path (when viewed along the axis of rotation 81 of drum 80, pawl-support plate 40, etc.) around a pawl-support plate 40 in the general manner shown in Figs. 2-5.
  • the at least one pawl 20 is configured so that upon rotation of pawl-support plate 40 around its axis of rotation 81, pawl(s) 20 will follow a generally circular orbital path 25 around axis of rotation 81.
  • drum 80 and pawl-support plate 40 are rotating at a rotational velocity w below a predetermined threshold value, all such pawls 20 will be in a first, disengaged position.
  • a pawl 20 will be actuated (i.e., caused to move from a first, disengaged position, toward and into a second, engaged position) when the velocity of the pawl 20 along its orbital path exceeds the predetermined threshold value.
  • a pawl 20 will not be not significantly affected (e.g. actuated) by any acceleration that the pawl may be experiencing, while in other embodiments such a pawl may be actuated by acceleration (and/or the velocity-actuation of the pawl may be modulated by the acceleration), as discussed in detail later herein.
  • a flexure-bome pawl is meant a pawl 20 that is attached to a flexure arm 30. Specifically, a trailing end 23 of pawl 20 will be attached to a leading end 31 of a flexure arm 30. Trailing end 32 of flexure arm 30 will be attached to a flexure arm anchor 50 as shown e.g. in Fig. 3.
  • a flexure arm 30 thus extends from flexure arm anchor 50 to pawl 20, and is elongate along this extent.
  • the path of a flexure arm, from anchor 50 to pawl 20, will often be at least generally circumferential, and may also extend at least generally radially outward, as will be evident from various exemplary arrangements presented in the Figures herein.
  • a flexure arm 30 or set of flexure arms 30 may exhibit a somewhat spiral appearance as evident in several Figures herein.
  • a flexure arm 30 is typically sheetlike or rodlike overmuch of its elongate length, e.g. so as to exhibit a thickness “t” (as indicated in Fig. 4) that is relatively small (e.g. by a factor of at least 10) in comparison to the overall elongate length of the flexure arm.
  • Flexure arm 30 is configured to deflect (e.g. bend) at least slightly, in a direction that is at least generally radially outward, to allow pawl 20 to move generally radially outward under the influence of centrifugal force as discussed below.
  • this deflection will take the form of reversible deformation that remains within the elastic limit of the material of which the flexure arm is made. It will further be appreciated that this deflection is an extremely low-friction process, the advantages of which are discussed later herein.
  • a flexure arm anchor 50 from which a flexure arm 30 extends is typically positioned axially adjacent to pawl-support plate 40, e.g. protruding axially away from pawl-support plate 40 (such terminology does not imply that such an anchor 50 must necessarily be an integral portion of plate 40, although in some embodiments it may be).
  • a flexure arm anchor 50 will be fixed in position relative to pawl-support plate 40; e.g., the anchor 50 may be non-movably attached to plate 40.
  • multiple individual pawls 20 may be respectively connected to multiple individual anchors 50 (e.g. in the form of individual posts).
  • some or all flexure arm anchors 50 may be integral portions of a pawl-support module 51 as seen most easily in Fig. 3. In some embodiments multiple flexure arm anchors 50 may be circumferentially spaced along the perimeter of a single (e.g. integral) pawl-support module 51, e.g. as in Figs. 4-5 herein.
  • a pawl 20 and a flexure arm 30 may be made separately and then attached to each other (e.g. as in the design of Fig. 10, discussed later herein).
  • a pawl and flexure arm may be attached to each other by way of being integral with each other, e.g. as in the design of Fig. 3.
  • integral and like terminology denotes items that are made in a single, common operation (e.g. by molding), as portions of a single unitary component.
  • a flexure arm 30 may be made separately from a flexure arm anchor 50 and then subsequently attached thereto.
  • a flexure arm 30 and a flexure arm anchor 50 may be integral.
  • a pawl, a flexure arm, and a flexure arm anchor 50 may all be integral with each other.
  • pawls and flexure arms may all be integrally connected to a single pawl -support module 51 as noted above and as illustrated in Fig. 3.
  • a pawl-support module 51 may be separately made from pawl-support plate 40 and may be attached to plate 40 e.g. by way of fasteners 45 that reside in orifices 47 of pawl-support plate 40 and orifices 53 of pawl-support module 51 as shown in Fig. 3.
  • a pawl -support module 51 (and possibly flexure arms 30) may be integral with pawl-support plate 40 rather than being made separately and then attached thereto.
  • a pawl-support module 51 will be fixed (not rotatable) relative to pawl-support plate 40.
  • flexure arm anchor does not require that an anchor must be e.g. a free-standing post; rather, a flexure arm anchor may simply be a local portion of a pawl-support module 51 from which a flexure arm extends.
  • a flexure-borne pawl 20 may be appreciated based on Figs. 4 and 5, which are plan views looking along axis of rotation 81. (These are conceptual views with various items omitted so that certain items and their function can be highlighted.) Pawls 20 and flexure arms 30 are configured so that when drum 80 (not shown in Figs. 4 and 5), pawl-support plate 40, and pawls 20, are not rotating (or are rotating slowly), pawls 20 will remain in a disengaged position as shown in Fig. 4.
  • a flexure-borne pawl 20 as disclosed herein will move generally radially outward from the disengaged position toward and into the engaged position, in a bodily manner.
  • moving “bodily” is meant that the pawl moves generally radially outward as a whole, in its entirety. That is, while in some instances the “leading” end 22 of a pawl 20 may move further radially outward than the “trailing” end 23 of the pawl 20, no portion of the pawl will move radially inward rather than outward.
  • a flexure-borne pawl is thus distinguished from, for example, a conventional pivot-mounted pawl that comprises a pivot point that is located within the perimeter of the pawl.
  • Such a pivot-mounted pawl is actuated by way of an engaging end of the pawl moving radially outward, and an opposite end of the pawl moving in the opposite direction, radially inward.
  • Some pivot-mounted pawls work in reverse fashion to this; however, such a pawl still has a portion that moves inward, and a portion that moves outward.
  • the only type of pawls that will be present in an arrangement as disclosed herein will be flexure-borne pawls, e g. no pivot-mounted pawl or pawls will be present.
  • flexure-borne pawls can advantageously minimize the amount of friction that arises in operation of the pawls. That is, a pivotal connection by which a pivot-mounted pawl is mounted to e.g. a post of a pawl-support plate, may exhibit friction due to the sliding of one surface against another as the pawl pivots. This friction may vary based e.g. on manufacturing tolerances, the presence of even small amounts of debris into the pivotal connection, and so on. In contrast, a pawl that is moved purely by the flexing of a flexure arm does not involve sliding of one surface against another to any significant extent.
  • pawls 20 and flexure arms 30 will be positioned so that they do not contact major surface 41 of pawl-support plate 40 to an extent that gives rise to significant frictional interaction.
  • the use of flexure-borne pawls can thus enhance the performance of a rotationally-activated braking device e.g. by minimizing variability in operating performance due to friction. It will also be appreciated that the use of flexure-borne pawls may offer advantages e.g. in terms of fewer parts being needed, and/or in allowing the use of a simplified manufacturing process.
  • a flexure-borne pawl differs from a conventional pivot- mounted pawl in another aspect.
  • a pivot-mounted pawl is biased by way of a biasing member (e.g. a spring) that serves to urge the pawl in a particular direction, which is typically limited by a physical stop.
  • the biasing member (e.g. spring) of a pivot-mounted pawl typically experiences at least some minimal force (e.g. tension) even when the apparatus is not being used.
  • a flexure-borne pawl when apparatus 1 is not being used, a flexure-borne pawl may be in a disengaged position that is a “home” position (i.e., a “neutral” position that the pawl will inherently assume when the drum is not rotating, or is rotating very slowly). In such a home position, the flexure arm 30 will not be experiencing any force that urges it radially inward or outward (in some instances, the only force that is operating may be gravity).
  • a flexure arm configured in this manner may not be subject to a near-continuous force in the manner of a conventional spring of a conventional pivot-mounted pawl.
  • a physical stop may be provided that, for example, may prevent the flexure arm from e.g. moving too far radially inward in the event that the apparatus is jostled or dropped.
  • such a physical stop may be positioned so that it causes the flexure arm to reside at least slightly away from (e.g. radially outward of) what would otherwise be its natural, “home” position.
  • design parameters e.g. the size, shape, mass, mass distribution, etc. of the pawls; and/or, the length, shape, thickness, and, in particular, the flexural modulus and bending stiffness, of the flexure arm
  • design parameters may be chosen in combination to provide that the pawl is actuated from a disengaged position to an engaged position at a predetermined threshold of rotational velocity.
  • One design parameter is the number of flexure-borne pawls that are present.
  • a single pawl may be used.
  • three pawls may be used, e.g. as in the exemplary arrangements of Figs. 2-5.
  • Figs. 6 and 7 illustrate an exemplary design in which two pawls are used (in these Figures, the various components use the same numbering as for corresponding components in Figs. 2-5). Any greater number of pawls (e.g. four pawls), may be used if desired.
  • pawls are provided in pairs (e.g.
  • each pair of pawls may be located in circumferentially-opposing positions from each other (i.e., on opposite sides of the axis of rotation 81 of drum 80 and pawl-support plate 40, when viewed along axis of rotation 81).
  • a pair of such oppositely-located flexure-borne pawls is depicted in exemplary embodiment in Figs. 6 and 7.
  • Each such pawl comprises a leading end 22 and a trailing end 23, and is attached to a leading end 31 of a flexure arm 30.
  • each flexure arm is attached to a flexure arm anchor 50; each such flexure arm anchor 50 is an integral component of a pawl-support module 51.
  • pawls 20, flexure arms 30, and flexure arm anchors 50 are all integral with a single, integral pawl-support module 51.
  • Figs. 4-5 and 7 reveal another useful design parameter, which is the amount of circumferential “wrap” exhibited by the combination of a pawl 20 and the flexure arm 30 that bears the pawl.
  • Such wrap may be characterized by the angle between two lines - one drawn from axis of rotation 81 to the tip of leading end 22 of pawl 20, the other drawn from axis of rotation 81 to the location at which the trailing end 32 of flexure arm 30 meets flexure arm anchor 50.
  • any particular pawl and its associated flexure arm may exhibit a wrap of at least 30, 45, 60, 90, 120, 150, or 180 degrees.
  • a pawl/flexure arm may exhibit a wrap of no more than 260, 200, 165, 135, 100, or 70 degrees. (In general, the greater the degree of “wrap”, the more a set of pawls and flexure arms may exhibit a shape that resembles a spiral.)
  • the exemplary pawls/flexure arms of Fig. 4 exhibit a circumferential wrap in the range of approximately 75 degrees; the exemplary pawls/flexure arms of Fig. 7 exhibit a circumferential wrap in the range of approximately 155 degrees.
  • FIG. 4 Various Figures herein (e.g. Figs. 4, 5, 7, and the later-discussed Figs. 11 and 12) depict an arrangement in which flexure arms are forwardly wrapped.
  • the flexure arms extend from their respective anchors to their junction with the pawls, in a direction that coincides with the above- described rotation direction (i.e., the direction of fall-induced rotation), as evident e.g. from Fig. 4.
  • the flexure arms are thus “pushing” the pawls in the rotation direction as the drum rotates.
  • this can be reversed, so that the flexure arms extend from their anchors to their junction with the pawls, in a direction that is opposite the rotation direction.
  • each pawl at which the flexure arm approaches the pawl will be the leading end of the pawl, and will be the engaging end that engages with a ratchet tooth.
  • the opposing end of the pawl will be the trailing end.
  • the long axis of at least a portion of a flexure arm 30 may have a selected orientation in relation to the orbital path (e.g. orbital path 25 as denoted in Fig. 4) followed by the pawl 20 that is borne by that flexure arm.
  • a long axis of a flexure arm 30 may be locally aligned with an orbital path to within a desired local alignment angle, along a chosen percentage of the elongate extent of the flexure arm.
  • inspection of Fig. 7 reveals that in this design, substantially the entire length of each flexure arm 30 is locally aligned (e.g.
  • Fig. 4 reveals that in this design, substantially the entire length of these flexure arms 30 is locally aligned within approximately 30 degrees of the orbital path that will be traced out by pawls 20. It is evident that in the design of Fig. 4, the local alignment is not as constant along the length of flexure arm 30 as it is in the design of Fig. 7; that is, in Fig. 4 the local alignment appears to vary from 0 degrees (exactly locally parallel, at certain locations) to approximately 30 degrees. Although it differs in other respects from the design of Fig. 4, the design of Fig. 11 similarly appears to exhibit a local alignment angle that varies, over the length of flexure arm 30, from 0 degrees to approximately 30 degrees.
  • a flexure arm may exhibit a local alignment angle, over any specified extent of the elongate length of a flexure arm, of e.g. less than plus or minus 70, 50, 40, 30, 20, 10, or 5 degrees. In further embodiments, any of these conditions may hold over at least 20, 40, 60, 80, 90, 95, or essentially 100 % of the elongate length of the flexure arm.
  • the measurement of such a local alignment angle, at any location along the elongate length of a flexure arm can be performed as follows.
  • a first line is drawn that coincides with the long axis of the flexure arm at least at that point (if the flexure arm is arcuate at that point, a line is drawn that is tangent to the flexure arm at that point).
  • a second line is drawn from axis of rotation 81, radially outward through that point. The second line is continued radially outward until it intersects the orbital path traced out by the pawl borne by that flexure arm.
  • a tangent to the orbital path is drawn at this point of intersection, which provides a third line. The angle between the third line and the first line provides the above-enumerated local alignment angle.
  • a flexure arm 30 may be relatively straight along its entire length, as in the design of Fig. 4.
  • a flexure arm 30 may be at least generally uniformly arcuate (i.e. with a local radius of curvature that does not vary by more than e.g. 20, 10, 5, or 2 %) along the entire length of the flexure arm, as in the design of Fig. 7.
  • a flexure arm may comprise a leading segment 33 and a trailing segment 38 that are connected by an elbow 34, as in the design of Fig. 11.
  • segments 33 and 38 may be relatively straight, with elbow 34 being more arcuate, also as evident in Fig. 11.
  • a flexure arm 30 may vary from being e.g. uniformly arcuate along most or all of its elongate length, to comprising any number of relatively straight segments interspersed with any desired number of e.g. sharply curved segments.
  • the thinnest dimension of the flexure arm may be oriented in a generally radially inward-outward direction, along at least a portion of the elongate length of the flexure arm.
  • the thickness “t” of the arm at that point may be at least generally aligned with a line that is drawn from axis of rotation 81 through that point.
  • the thickness “t” may be aligned within plus or minus 50, 30, 20, 10, or 5 degrees of radially inward-outward, e.g. along at least 20, 40, 60, 80, 90, or 95 % of the elongate length of the flexure arm.
  • FIG. 1 Various figures herein depict exemplary arrangements in which a relatively sharp demarcation is present between a pawl 20 and a flexure arm 30 to which the pawl is attached.
  • a flexure arm could gradually increase in thickness (whether smoothly or stepwise) from its trailing end to its leading end, with a leading portion of the flexure arm being sufficiently thick (and e.g. massive) to serve as a pawl. All such designs fall within the overall concept of a flexure-borne pawl and a flexure arm to which such a pawl is attached.
  • a flexure arm could comprise an elongate slot that extends along the long axis of at least a portion of the flexure arm; in fact, in some embodiments a pawl could be connected to a flexure anchor by way of two (or more) elongate flexure arms that are separate from each other along a portion, or the entirety, of their length.
  • a pawl that is “attached” to a flexure arm does not necessarily require that the pawl must be permanently attached, e.g. adhesively bonded or welded, to the flexure arm.
  • a pawl may e.g. comprise a slot and a seating cavity configured to respectively accept a leading portion of the flexure arm and an enlarged seating head at the terminal end of the flexure arm.
  • the enlarged seating head and leading portion of the flexure arm may be inserted into these openings e.g. as shown in Fig. 11 to attach the pawl to the flexure arm.
  • Arrangements of this general type fall within the overall concept of a pawl that is attached to a flexure arm.
  • the flexure arms may be made of a material with a suitable flexural modulus (and with properties that will be maintained over aging).
  • the flexure arms may be made of a suitable metal, e.g. stainless steel.
  • the flexure arms may be made of a suitable engineering plastic, e.g. polyether ether ketone (PEEK), acrylonitrile -butadiene -styrene (ABS) polymers, carbon-fiber reinforced polymers (of any suitable polymeric composition), and so on.
  • PEEK polyether ether ketone
  • ABS acrylonitrile -butadiene -styrene
  • the flexure arms may be made by injection molding of any such material.
  • flexure arms, pawls that are attachable to flexure arms; or, a pawl-support module that integrally includes flexure arm anchors, flexure arms, and, in some embodiments, the pawls themselves, may be made of injection-molded metal.
  • flexure arms and/or pawls that are attachable to flexure arms; or, a pawl-support module that integrally includes flexure arm anchors, flexure arms, and, in some embodiments, the pawls themselves, may be made of an amorphous metal.
  • an amorphous metal is meant a metal or metal alloy (most such materials are in fact alloys) that exhibits a disordered, i.e. non-crystalline, atomic-scale structure that is characterized by a near-complete absence of grain boundaries.
  • Such a material may be molded to form a flexure arm or even to form an entire pawl-support module and integral flexure arms (and optionally, pawls) thereof.
  • Such materials may have unique properties (e.g., a combination of flexural modulus, yield strength, and durability) that render them highly useful to serve as flexure arms for the uses herein.
  • Such materials may be made of any suitable alloy (e.g. a zirconium-based alloy) and may be formed into the desired items by any suitable method, e.g. by injection molding.
  • a pawl-support plate 40 may comprise at least one buttress 60 that protrudes axially from the pawl-support plate (e.g. from major surface 41 of plate 40, on the same side of the plate that the pawls and flexure arms are present), as shown in exemplary embodiment in Fig. 3.
  • a buttress 60 can be an integral part of pawl-support plate 40; in other embodiments, such a buttress may be made separately and then attached to plate 40.
  • Such a buttress 60 can be positioned so that at least a portion of the buttress 60 is positioned circumferentially rearward of at least a portion of the trailing end 23 of pawl 20, as shown in exemplary embodiment in Fig. 4. (Often, at least a portion of the buttress may be positioned at least generally radially outward of at least a portion of pawl 20, also as evident in Fig. 4).
  • a buttress 60 will comprise a contact surface 61 (indicated in Figs. 3 and 4) that is configured to be contacted by a portion of trailing end 23 of pawl 20 under certain conditions, as explained below.
  • pawl 20 and buttress 60 are configured so that a circumferential gap 52 (which may be relatively small, as evident in Fig. 4) is present between contact surface 61 of buttress 60, and trailing end 23 of pawl 20, e.g. at their point of closest approach.
  • Gap 52 will typically be present when the pawl is in a disengaged position (in other words, during ordinary use of apparatus 1, no portion of pawl 20 will typically be in contact with any portion of buttress 60).
  • Such a gap 52 may be present momentarily after pawl 20 has moved radially outward into an engaged position, before being eliminated as described below.
  • a pawl 20 In a braking (e.g. fall-arrest) operation, a pawl 20 will move generally radially outward so that a leading end 22 of the pawl engages with a tooth 91 of a ratchet 90, as described earlier herein and as shown in Fig. 5. This will bring pawl 20 to a sudden stop and will develop considerable force on the pawl 20, acting in a generally circumferentially-rearward direction as indicated by block arrow 29 in Fig. 5. This force will urge pawl 20 slightly circumferentially rearward far enough to close gap 52 and thus to cause at least a portion of trailing end 23 of pawl 20 to come into contact with the contact surface 61 of buttress 60. In other words, engaging of the leading end of the pawl with the ratchet can cause the trailing end of the pawl to be “jammed” into the leading end of the buttress.
  • Buttress 60 can be configured to be extremely strong (e.g. in comparison to flexure arm 30). Buttress 60 can thus bear, and dissipate, at least a portion of the force that is developed on the pawl upon the engaging of the pawl with the tooth of the ratchet. In various embodiments, the buttress may bear and dissipate a significant amount of this force (e.g. 60, 80, 90, 95, 98, or essentially 100 % of the force).
  • any number of buttresses may be used, e.g. one, two, three, four or more.
  • the number of buttresses may equal the number of pawls (e.g., three and three as in the design of Fig. 2, or two and two as in the design of Fig. 14, which is discussed in detail later herein).
  • each buttress may be positioned in relation to a particular pawl so that upon engaging of the pawl with a ratchet tooth, the pawl will be jammed against that particular buttress.
  • the providing of a buttress in this manner can substantially eliminate any need to strengthen flexure arm 30 to be able to bear the full amount, or even a significant portion, of the force that develops when the pawl engages a ratchet tooth.
  • a flexure arm that is optimized to provide the desired flexibility might, for example, irreversibly deform (e.g. buckle or accordionize) under the large force that develops when the pawl engages a ratchet tooth in the course of arresting a fall.
  • a pawl 20 in a fall-arrest event, may be urged slightly circumferentially rearward in such manner as to e.g. momentarily slightly deflect its flexure arm 30; however, such deflection will be below the elastic limit of the flexure arm and will be reversible.
  • a buttress with a forwardly-wrapped configuration of flexure arms and pawls as defined and described previously herein.
  • a rearwardly- wrapped configuration of flexure arms and pawls may be used.
  • any such buttress(es) can be used and can still be configured so that the engaging of the leading end of a pawl with a ratchet will cause the trailing end of the pawl to be “jammed” into the leading end of the buttress.
  • the primary difference will be that in this case the trailing end of the pawl will be the end that is generally opposite the end from which the flexure arm approaches the pawl.
  • the trailing end 23 of pawl 20, and contact surface 61 of buttress 60 may exhibit complementary shapes to ensure that trailing end 23 is guided into a desired contact position with buttress 60. Any such design should also ensure that the pawl can be separated from contact with the buttress 60 after the force is removed. This is in view of the fact that some fall -protection apparatus are occasionally subjected to “lock-up” testing e.g. in which an operator pulls rapidly on the safety line 115 to ensure that the braking device properly engages to arrest the motion. At the end of such a test, the apparatus and braking device thereof should return to their previous, disengaged-and-ready, condition.
  • a buttress 60 (and other components of the braking device) should be configured to provide that the actuation of a flexure- borne pawl is not an irreversible process. Exemplary designs that may facilitate these characteristics are visible in Figs. 3 and 4, and particularly in Figs. 10-12.
  • the value of velocity that causes a flexure-borne pawl 20 to be actuated can be set as desired.
  • a velocity threshold maybe set to any suitable nominal value, e.g. 6, 8, or 10 feet per second.
  • Such a nominal value will correspond to the linear velocity experienced by the extended portion of safety line 115 (and thus to a user connected thereto).
  • This can be converted to an actual value of rotational velocity of pawl 20 in view of the specific design parameters of the fall -protection apparatus (e.g. the diameter of the drum from which the safety line is unwound, the diameter of the orbit of the pawl, and so on).
  • This can be used to set particular parameters (e.g. the bending stiffness of a flexure arm 30, and so on) to ensure that pawl 20 is actuated at a rotational velocity that corresponds to the desired threshold of velocity experienced by the user.
  • a flexure arm may be the only item and mechanism by which the force-displacement relationship of a flexure-borne pawl is established
  • one or more additional methods of biasing may be used as an adjunct to the flexure arm.
  • one or more biasing springs e.g. coil springs acting in tension
  • magnetic biasing may be used as an adjunct to the flexure arm.
  • a magnet may be installed in a side of a pawl-support module, e.g.
  • a magnet may be installed in the pawl in addition to, or instead of, a magnet being present in the pawl-support module. That is, depending e.g. on the metal of which the pawl and/or the pawl-support module is made, in some embodiments only one magnet, interacting with a suitable metal, may be sufficient to achieve the desired effects. In other embodiments a pair of magnets may be used, acting on each other in combination. Any such magnet(s) may be configured to achieve an attractive force or a repelling force that may act in combination with the stiffness of the flexure arm to provide a desired force-displacement relationship.
  • any such flexure-borne pawl may be configured to be relatively insensitive to acceleration.
  • the presence of acceleration may e.g. slightly augment the actuation due to velocity, or slightly reduce or retard the actuation due to velocity.
  • the pawl(s) and flexure arm(s) may be configured so that any such effect of acceleration is relatively insignificant.
  • a rotationally-activated braking device of a fall-protection apparatus may be configured to purposefully rely on acceleration for actuation (and/or for modulation of the response to velocity) in at least some circumstances.
  • a rotationally-activated braking device of a fall-protection apparatus may be configured to purposefully rely on acceleration for actuation (and/or for modulation of the response to velocity) in at least some circumstances.
  • pawl 20 upon rotation of drum 80, one or more pawls 20, and so on, above a predetermined threshold of acceleration (a), pawl 20 will be urged bodily away from a disengaged position, radially outward toward and into an engaged position in which it engages a tooth of the ratchet.
  • a pawl-support plate 40 and a drum 80 have a fixed relationship so that plate 40 is not able to rotate relative to drum 80 and vice versa.
  • a pawl -support plate 40 may be fixedly attached to (e.g. bolted to), drum 80.
  • both plate 40 and drum 80 may be keyed to common shaft 82 so that they cannot rotate relative to each other.
  • a pawl-support plate 40 and a dmm 80 may sandwich a layer of friction material 122 therebetween, as shown in Fig. 2.
  • Such a configuration allows that, in the event that the rotation of plate 40 is stopped upon a pawl being actuated, limited rotation of drum 80 relative to plate 40 may occur before being stopped by the action of the friction material, as discussed later herein. Such an occurrence still requires a great deal of force in order for any relative rotation of plate 40 and drum 80.
  • pawl-support plate 40 and drum 80 may be configured so that they are relatively easily able to rotate relative to each other through a predetermined arc of partial rotation of e.g. at most 90 degrees, 180 degrees, or 270 degrees. That is, they may be configured so that they can rotate relative to each other due to an acceleration-derived force arising from a user fall, rather than being fixed to each other or only being able to rotate relative to each other upon being exposed to a very high force such as encountered when a pawl is engaged with a ratchet.
  • the pawl-support plate will usually remain in a “home” position relative to the drum, with the drum and the pawl -support plate rotating in lockstep.
  • FIG. 8 depicts a drum 80, pawl-support plate 40, and pawls 20.
  • Other components are omitted for clarity, but it will be appreciated that such components can be provided in a fall-protection apparatus e.g. of the general type shown in Figs. 1 and 2, with the items shown in Figs. 8 and 9 being substituted for the corresponding items of Fig. 2.
  • no layer of friction material is present between drum 80 and pawl-support plate 40.
  • a major sidewall 87 of drum 80 which sidewall comprises a major surface 83 that may be in at least occasional contact with a major surface of 42 of pawl-support plate 40, may have a low coefficient of friction.
  • the entirety of drum 80 may be made of a material that has a low coefficient of friction.
  • sidewall 87 be a separately made item (as evident in Fig. 9) that is chosen to have a low coefficient of friction.
  • such a sidewall 87 may be made of e.g. poly(oxymethylene), poly(tetrafluoroethylene), and similar organic polymeric materials.
  • the major surface 83 of sidewall 87 may be treated, coated, or otherwise configured to have a low coefficient of friction.
  • a low-friction spacer e.g. a disc made of poly(oxymethylene) may be present between plate 40 and sidewall 87. Any such arrangement or combination thereof can provide that plate 40 and drum 80 are able to rotate relative to each other to a sufficient amount to achieve the effects described below.
  • the desired acceleration-actuation can be provided by using one or more camming bollards 84 as shown in exemplary embodiment in Fig. 9.
  • a camming bollard 84 will be in a fixed position relative to drum 80 (although it may not necessarily need to be attached or bonded to drum 80; e.g., it may be sufficient that an end of the bollard is seated in a cavity provided in drum 80 as shown in Fig. 9).
  • Camming bollard 84 protrudes axially from drum 80 (toward the side of the drum that the pawl-support plate, pawls, and so on, are present, as is evident in Fig. 9).
  • Camming bollard 84 extends through an elongate slot 43 in pawl -support plate 40 (slots 43 are most easily visible in the isolated exploded view of Fig 10, noting that the camming bollards 84 are omitted from this Figure). This provides that a portion of camming bollard 84 resides within a space 44 that is radially inward of pawl 20 and/or is radially inward of a leading segment of flexure arm 30. This arrangement is most easily seen in Fig. 11, which is a plan view looking along the axis of rotation of the drum and pawl-support plate.
  • Such an arrangement can be configured so that upon acceleration of drum 80 (in the direction denoted co, a in Fig. 11) above a predetermined threshold value of acceleration a, pawl-support plate 40 will rotate circumferentially rearwardly (away from plate 40’s “home” position relative to drum 80), in the direction indicated by arrow 46 in Fig. 11.
  • acceleration of drum 80 will cause support plate 40 to momentarily “lag” behind drum 80, due to the mass of the support plate, pawls, and so on.
  • each pawl 20 will move circumferentially rearwardly relative to drum 80 and thus relative to a camming bollard 84 that is in a fixed position on drum 80.
  • This movement of pawl 20 will cause a radially-inward contact surface 27 of pawl 20 to impinge on camming (contact) surface 85 of camming bollard 84.
  • This impingement will have the effect that, as pawl 20 slidably moves circumferentially rearward relative to camming bollard 84, bollard 84 will urge pawl 20 generally radially outward.
  • Pawl 20 wrll thus be motivated generally radially outward, toward and e.g. into an engaged position in which an engaging end of the pawl engages a tooth of the ratchet, as can be seen by inspection and comparison of Figs. 11 and 12.
  • the movement of pawl 20 will be “bodily” movement as described earlier herein.
  • radially-inward contact surface 27 of pawl 20 may be configured so that impingement of this surface on camming surface 85 causes pawl 20 to be urged generally radially outward (in some embodiments pawl 20 may also be urged slightly circumferentially rearward, as well).
  • contact surface 27 may be a radially-inwardly-sloping surface. By this is meant that as surface 27 is traversed in a leading direction (the direction of rotation co), the surface is located further and further radially inward, as is evident from Fig. 11. This, combined with the above-described flexibility of flexure arm 30, provides that as pawl 20 slidably moves along camming surface 85 of camming bollard 84, pawl 20 will be urged bodily outward.
  • the elongate slot 43 in pawl-support plate 40, through which camming bollard 84 extends, may exhibit a long axis that is at least generally locally aligned with the orbital path followed by pawl 20, as is evident from Figs. 11 and 12.
  • a camming bollard 84 may be positioned in the above-mentioned space 44 so that when the dmm and pawl-support plate are not rotating (or are rotating very slowly), camming bollard 84 is not in contact with any portion of pawl 20 or flexure arm 30.
  • a camming bollard 84 may be positioned in the above-mentioned space 44 so that when the dmm and pawl-support plate are not rotating (or are rotating very slowly), camming bollard 84 is not in contact with any portion of pawl 20 or flexure arm 30.
  • other embodiments e.g. as evident in Fig.
  • camming bollard 84 may be in contact with a portion of pawl 20 and/or flexure arm 30.
  • Camming bollard 84 thus may, in some embodiments, serve as a physical stop that prevents pawl 20 and/or flexure arm 30 from moving radially inward.
  • the effect of a camming bollard 84 on a pawl 20 may be achieved purely through physical contact.
  • a camming bollard and/or a pawl 20 may have a magnet installed therein.
  • a magnetic force e g. a repelling force
  • the one or more camming bollards 84 may be part of a load-bearing (force-transmitting) path between drum 80 and pawl-support plate 40.
  • camming bollards 84 may be made of any suitable material, e.g. steel.
  • the far end of each bollard e.g., the far right end of bollards 84 as shown in Fig. 9 may be seated in a receptacle of drum 80, which receptacle may be reinforced to enhance the load-bearing and load-transmitting properties of the interface between the drum and the camming bollard.
  • a receptacle is visible, unnumbered, in the dram of Fig. 9.
  • bollards 84 may serve purely for the purposes of camming as described earlier herein; if so, some other posts or similar features may be provided that serve as part of a load-bearing path between plate 40 and dram 80.
  • Dram 80 may be made of any material that exhibits properties commensurate with the desired strength.
  • dram 80 may be made of a molded polymer such as e.g. glass-fiber-reinforced nylon; or, drum 80 may be made of a metal such as e.g. cast aluminum.
  • pawl-support plate 40 may be made of any material with suitable properties, e.g. steel.
  • the camming bollards may serve as physical stops that limit the rotation of dram 80 relative to pawl-support plate 40. That is, in some embodiments the rotation of dram 80 relative to plate 40 may be limited by the distance that camming bollard 84 can travel within the elongate length of slots 43 of plate 40, as is evident from inspection of Figs. 11 and 12. That is, in some embodiments, the length of an elongate slot 43 of pawl-support plate 40, in combination with the presence of a bollard 84 that extends therethrough, can define the limits of the arc of rotation of pawl-support plate 40 relative to drum 80.
  • the length of an elongate slot 43 can be set so that this arc of rotation is at least 5, 10, 15, 20, or 25 degrees. In further embodiments, the length of elongate slot 43 can be set so that this arc of rotation is at most 80, 70, 60, 50 or 40 degrees. (The particular slots 43 depicted e.g. in Fig. 12 appear to establish an arc of rotation of approximately 35 degrees.)
  • a single type of pawl may be configured so that it can be actuated by absolute velocity, and/or can be actuated by acceleration.
  • the actuation of a flexure-borne pawl 20 by acceleration, and by velocity may be at least generally independent of each other.
  • a pawl 20 may be actuated upon the rotational velocity of the pawl exceeding a certain threshold value, substantially regardless of the acceleration that exists when that threshold value of velocity is reached, and substantially regardless of the particular acceleration history that was experienced by the pawl in reaching that threshold value of velocity.
  • a pawl 20 may be actuated upon the acceleration of the pawl exceeding a certain threshold value, substantially regardless of the absolute value of the velocity that exists when that threshold value of acceleration is reached, and substantially regardless of what velocity may or may not have been experienced by the pawl prior to reaching that threshold value of acceleration. (By substantially regardless is meant that a parameter contributes less than 10 % to the effect in question.)
  • the predetermined threshold values of velocity and acceleration may be set substantially independently of each other. This will have advantages that are readily appreciated by ordinary artisans.
  • it may be advantageous that the acceleration serves to modulate the response to velocity, e.g. to lower the threshold value of velocity-actuation.
  • the acceleration that causes actuation of a pawl 20 corresponds to a change in the magnitude of the velocity of a body along its orbital path. Acceleration that results merely from the body following an orbital path at constant velocity (i.e., centripetal acceleration) has little or no effect; the velocity of the body along this orbital path must change in order for acceleration-actuation of the type disclosed herein to occur.
  • the value of acceleration that causes a pawl 20 to be actuated can be set as desired.
  • Such an acceleration threshold may be set to any suitable nominal value, e.g. 0.6 to 0.8 g. This is a nominal value that corresponds to the linear acceleration experienced by the extended portion of safety line 115 (and thus to a user connected thereto). This can be converted to an actual value of acceleration of pawl 20 in view of the specific design parameters of the fall -protection apparatus (e.g. the diameter of the drum from which the safety line is unwound, the diameter of the orbit of the pawl, and so on) . This can be used to set particular parameters that ensure that pawl 20 is actuated at a rotational acceleration (specifically, a tangential acceleration) that corresponds to the desired threshold of acceleration experienced by the user.
  • a rotational acceleration specifically, a tangential acceleration
  • a drum 80 may comprise a main section that includes one major sidewall, with another major sidewall 87 being a separately-made item that is then combined with the main section to provide drum 80 (and to establish a space 88 between the sidewalls, that accepts the wound-up length of safety line 115).
  • pawl-support plate 40 can comprise buttresses 60 that function in a similar manner as described earlier herein.
  • Pawl-support module 51 including flexure arm anchors 50 and flexure arms 30, can be attached to plate 40 e.g. by fasteners 45.
  • pawl-support module 51 and flexure arms 30 are integral; however, pawls 20 are separately made and are attached to the leading ends of flexure arms 30.
  • Various aspects of the pawls, flexure arms, and so on (e.g. the amount of circumferential wrap and so on) of this design have already been discussed herein.
  • the arrangements disclosed herein can allow a flexure arm 30 to be configured (e g. to have the desired flexibility/stiffhess) to allow a pawl 20 to be actuated by a predetermined velocity, and/or by a predetermined acceleration.
  • the providing of a buttress 60 to substantially free the flexure arm from having to bear a high load upon the pawl being engaged with a ratchet tooth can enable the freedom to design the flexure arm to achieve both of these goals.
  • a dedicated biasing mechanism may be provided that urges pawl-support plate 40 circumferentially forward (i.e., in a leading direction) relative to drum 80, so that plate 40 can be returned to its home/ready position at the conclusion of a lock-up test.
  • a biasing member 86 e.g. a torsion spring as discussed previously
  • Such biasing members are conventionally configured to retract line 115 (and thus to remove any slack in line 115) if the user moves toward the apparatus.
  • this biasing of drum 80 may be sufficient to serve the purpose of restoring pawl-support plate 40 to its home position after a lock-up test.
  • such a biasing member of drum 80 may perform “double-duty” and eliminate any need to provide a dedicated biasing mechanism for pawl-support plate 40.
  • a dedicated biasing mechanism may be provided for pawl-support plate 40, e.g. to bias plate 40 relative to drum 80.
  • Various mechanisms and arrangements by which a pawl-support plate may be biased relative to a drum are described in detail in U.S. Provisional Patent Application No. 62/705,535, filed 2 July 2020, entitled Fall-Protection Apparatus Comprising Braking Device With Velocity-Actuated, Acceleration- Modulated Pawl(s), which is incorporated by reference herein in its entirety.
  • acceleration-actuated pawls as an adjunct to a braking system that relies on velocity-actuated pawls that are flexure-borne pawls.
  • the concept of an acceleration-actuated pawl as achieved e.g. by a camming system as disclosed herein is independent of any requirement that the pawl must be flexure-borne.
  • an ordinary artisan will appreciate that a system of camming bollards or like mechanisms, could be applied to pivot-mounted pawls of the general type described earlier here.
  • Such pawls can thus pivot into an engaged position upon exceeding a predetermined threshold of velocity, and/or, such pawls could be motivated to pivot into an engaged position by way of the pawl impinging onto a camming bollard of the general type described above, as the result of sufficient acceleration.
  • a camming system as described above may be used to provide an acceleration-actuated braking system. That is, in some embodiments the pawls and associated components may be configured so that they are far more likely to be actuated by acceleration than by absolute velocity.
  • an acceleration-actuated braking device that relies on a camming system as described herein may be used without regard to whether the braking device is able to be velocity-actuated. Such arrangements and uses are within the scope of the disclosures herein.
  • the arrangements herein cause at least one pawl to engage with a tooth 91 of a ratchet 90 as indicated in exemplary embodiment in Fig. 7.
  • This can either stop the rotation of drum 80 directly (e.g. in the case of a “hard-stop” arrangement as mentioned earlier herein), or can activate a friction brake that brings the rotation of drum 80 to a halt.
  • ratchets and the manner in which one or more pawls engage with a tooth of the ratchet, are possible.
  • any such pawl will be configured so that the engaging end 22 of a pawl 20 (in fact, the entirety of the pawl 20) will travel from a disengaged position to an engaged position by moving generally radially outward.
  • a radially-inward-facing ratchet meaning a ratchet, e.g. a ratchet ring or partial ring, with radially inward-facing teeth.
  • a ratchet rather than being provided e.g. as a toothed ring that is made separately and inserted into a housing of a fall-protection apparatus, may be provided e.g. as an integral (e.g. molded, cast, or machined) feature of the housing of the apparatus.
  • the PROTECTA fall-protection apparatus available from 3M Fall Protection, Red Wing, MN, and discussed in more detail below, is an example of a product that uses this type of ratchet. Another possible variation in ratchet design is presented in U S.
  • Patent 9488235 in which a ratchet takes the form of a single tooth (“stop member”) that is provided as an integral part of a bracket (e.g., a load-bearing bracket) of a fall-protection apparatus.
  • stop member e.g., a load-bearing bracket
  • the ratchet 90 depicted in Figs. 11 and 12 herein is another example of a ratchet that comprises only a single tooth 91, as is clear from Figs. 11 and 12.
  • a ratchet of a rotationally-activated braking device can be any component (e.g. a toothed ring, a partial ring, or a portion of a fall-protection bracket or housing, and so on) that presents at least one tooth that can be engaged by an engaging end of a pawl to initiate a braking operation of the rotationally-activated braking device.
  • ratchet is used for convenience of description; use of this term does not require that the ratchet and pawl(s) must necessarily be arranged e.g so that relative rotation of these components is permitted in one direction but is precluded in the opposite direction. (However, the ratchet and pawl(s) can be arranged so that such functionality is provided if desired.)
  • a rotationally-activated braking device as disclosed herein can bring a drum to a “hard stop” (e.g. the braking device may rely on a ratchet that is non-rotatably fixed to the housing of the apparatus), as discussed earlier herein.
  • a rotationally-activated braking device as disclosed herein will comprise (e.g. will work in concert with) a friction brake.
  • a friction brake will comprise at least one layer of friction material and at least one rotatable member, with a friction-braking surface of the layer of friction material being in contact (typically, at all times during ordinary use of the fall-protection apparatus) with a contact surface of the rotatable member.
  • a rotatable member is meant an item (e.g., a disk, ring, rotor, or the like) that is configured so that the member and the layer of friction material can be set into rotating motion relative to each other upon sufficient differential torque being applied to the layer of friction material and the rotatable member as the result of the engaging of a pawl with a ratchet of the rotationally-activated braking device.
  • the friction braking surface of the layer of friction-braking material and the contact surface of the rotatable member are constantly pressed together to provide sufficient static frictional force that, as a human user moves about a workplace in ordinary use of the apparatus, there is no relative motion between the two surfaces.
  • a ratchet of the rotationally-activated braking device may serve as a rotatable member of the friction brake of the braking device.
  • the ratchet is able to rotate with respect to the housing of the apparatus, but typically remains stationary during ordinary use of the apparatus. That is, the dram may rotate (relatively slowly) relative to the housing to extend and retract the safety line as a human user moves about a workplace.
  • the ratchet not being subjected to any rotational force, and being frictionally constrained by one or more layers of friction material, does not rotate relative to the housing.
  • the engaging end of a pawl engages with a tooth of the ratchet and overcomes this frictional constraint and causes the ratchet to rotate relative to the layer(s) of friction material and thus relative to the housing of the apparatus.
  • the friction between the friction-braking surface of the friction material and the contact surface of the ratchet then slows or halts the rotation of the ratchet relative to the housing of the apparatus thus slowing or halting the rotating of the rotatable drum relative to the housing of the apparatus.
  • the assembly shown in exploded view in Fig. 13 is one example of this general type of friction brake.
  • Such an assembly may rely on a ratchet 90 that, along with a layer of friction material 122, is sandwiched between a pressurization ring 125 and a backing plate 126.
  • Ring 125 and plate 126 may be pressed together (e.g. by way of bolts that pass through the various orifices visible in Fig. 13) with a desired force that imparts the desired frictional characteristics.
  • Fig. 13 are merely one way of achieving such functionality; various modifications are possible (for example, rather than pressurization ring 125 and/or backing plate 126 being a separately-made item that is installed into a housing of a fall- protection apparatus, a portion of the housing itself may serve such a role).
  • a ratchet may comprise two contact surfaces and may be sandwiched between two layers of friction material.
  • a ratchet of a friction brake may only comprise a single contact surface which may be in contact with only a single layer of friction material.
  • the rotatable member of a friction brake of a rotationally-activated braking device may not necessarily be a ratchet of the braking device. Rather, in some cases the ratchet of the rotationally-activated braking device and the rotatable member of the friction brake of the rotationally- activated braking device may be separate items.
  • a pawl- support plate 40 may serve as a rotatable member of the friction brake.
  • a layer of friction material 122 may be arranged in between the pawl-support plate 40 and drum 80, with a first major frictional surface 123 of friction material 122 in contact with a contact surface 42 of plate 40 as indicated in Figs. 2 and 3 herein.
  • a second major frictional surface 124 of friction material 122 may similarly be in contact with a contact surface of drum 80.
  • the entire assembly can be pressed together to impart the desired frictional characteristics between these surfaces. (It will be appreciated that such an arrangement would not likely be used in embodiments in which drum 80 and pawl-support plate 40 are desired to have freedom of relative rotation, e.g. in the event that camming-derived acceleration-actuation is desired.)
  • the engaging of an engaging end of a pawl with a tooth of the ratchet will cause the pawl-support plate 40 on which the pawl is mounted to near-instantaneously cease rotating, while drum 80 may continue to rotate momentarily.
  • the frictional force between the contact surface of rotatable member (pawl-support plate) 40 and the first friction-braking surface of the layer of friction material 122, and/or between the contact surface of the drum and the second friction-braking surface of the layer of friction material will slow or halt the rotation of the drum. Often, the drum may be brought to a halt before the drum has completed, for example, one full revolution.
  • the layer of friction material may be e.g.
  • a separate plate e.g. attached to the drum or co-mounted on a common shaft so that the separate plate is not rotatable relative to the drum, may provide a contact surface for a layer of friction material, rather than having the friction material directly in contact with a wall of the drum.
  • a layer of friction material may itself be disposed on (e.g. laminated or bonded to) a support plate as discussed herein.
  • a layer of friction material may be “free-standing” rather than being bonded to a support plate. Any suitable friction material may be used, e.g. cork, rubber, and so on.
  • Friction materials that may be particularly useful are described in U.S. Patent Application 16/630584 and in corresponding PCT Published Application WO2019/012454, both of which are incorporated by reference herein in their entirety. The above discussions make it clear that any compatible type, design or arrangement of ratchet, friction material, and so on, may be used in combination with the herein-disclosed arrangement of pawls.
  • Fig. 14 depicts, in exploded view, an exemplary arrangement of a fall protection apparatus (a self-retracting lifeline) that is somewhat similar to that depicted in Fig. 2, with differences as noted below.
  • Fig. 15 is a nonexploded perspective view of the apparatus of Fig. 14 with the pawl-support plate (40) omitted so that other items can be seen.
  • Fig. 14 and 15 show various components of the apparatus, with some entities, e.g. housing pieces and various ancillary items, being omitted for clarity.
  • a ratchet is not depicted in Figs. 14 or 15; any suitable rachet may be used, e.g. of the type depicted in Fig. 2.
  • a suitable friction material may be included if desired.
  • Rotationally-activated braking device 10 comprises pawls 20, flexure arms 30, a pawl-support module 51, and a pawl-support plate 40 to which the pawl- support module 51 is fixedly attached.
  • This attachment can be achieved by passing any suitable fasteners, e.g. screws or bolts, through orifices 53 of pawl-support module 51 and corresponding, aligned orifices 47 of pawl-support plate 40.
  • any suitable fasteners e.g. screws or bolts
  • abuttress that is located on a dram sidewall cannot move relative to the sidewall, and the dram sidewall cannot rotate relative to the remainder (other components) of the dram.
  • a buttress may be e.g. integrally molded with sidewall 87 or may be made separately and then attached to sidewall 87.
  • sidewall 87 may be formed (e.g. molded) as an integral portion of dram 80.
  • sidewall 87 may be a separately-made piece that is e.g. mounted on a common shaft (not shown in Fig. 14) with the other components of drum 80.
  • a sidewall 87 may be fixed in position relative to the other components of dram 80 e.g. by providing sidewall 87 with a mating feature (e.g. an orifice 94 or a post) that is mated to a complementary mating feature (e.g. a post 95 or an orifice) of a main portion of dram 80 as evident in Fig. 14.
  • sidewall 87 and the other components of dram 80 may be mounted on a common shaft in such manner as they cannot rotate relative to each other.
  • such a sidewall 87 may be physically attached (e.g. bolted) to another component of dram 80; in other embodiments, sidewall 87 may not necessarily be attached in this manner but nevertheless will be configured so that sidewall 87 cannot rotate relative to the remainder of dram 80.
  • sidewall 87 of dram 80 will not be rotatable relative to dram 80. Buttresses 60, being on sidewall 87, will thus be in a fixed position relative to drum 80, rather than being on a pawl-support plate 40 that is capable of rotating at least to a certain extent relative to dram 80 as in the design of Fig. 2 Although either arrangement may be preferable in various circumstances, a design in which the buttresses are on the dmm sidewall may offer advantages at least in some instances.
  • positioning buttresses 60 on the sidewall of the dmm upon which the safety line 115 of the fall-protection apparatus is wound can provide that the forces that are developed when a pawl 20 engages with a ratchet tooth (not shown in Fig. 14) are transmitted through a buttress 60 into dmm 80 rather than into a pawl-support plate 40 as in the previously-described designs. This can, in the event of a user fall, minimize any fall-arrest force that is transmitted through pawl-support plate 40 into a bearing 70 upon which pawl-support plate 40 rotates.
  • bearing 70 This reduction in the need for bearing 70 to withstand heavy loads can allow the design of bearing 70 to be simplified (e.g., so as to be a simple sleeve or bushing as illustrated in Fig. 14) and/or to be configured for optimum performance of the braking device under particular conditions.
  • pawl-support plate 40 and dmm sidewall 87 are separate items (with buttresses on the dmm sidewall)
  • a dmm sidewall itself could serve as a pawl-support plate (and could have buttresses thereon).
  • the buttresses are mounted on a dmm sidewall 40 that, by definition, is not acting as a pawl-support plate, that function being served by a separate pawl-support plate 40.
  • Figs. 14-15 differs from that of Fig. 2 in another aspect.
  • pawl-support plate 40 to which pawl-support module 51 (or, a collection of independent flexure arm anchors 50) is fixedly attached
  • the buttresses will remain in a fixed circumferential position relative to the flexure arm anchors 50 and thus to the path of the pawl.
  • Such an arrangement may require the pawls and flexure arms to be configured so that when a pawl moves radially outward to an engaged position (as illustrated by block arrow 28 of Fig. 4), the trailing end of the pawl will be positioned closely in front of (i.e. in a “leading” direction) the leading end of the buttress.
  • drum 80 and buttresses 60 thereon, and pawl-support plate 40 and pawls 20 thereon, are all moving in the w direction in terms of absolute motion, but the mass of the latter components provides that these components can momentarily “lag” the former components in their rate of motion.
  • a buttress can thus move circumferentially “forward” toward an optimal position for receiving an engaged pawl (i.e., can reduce circumferential gap 52 so that the engaged pawl can be “jammed” against the buttress with minimum force on the pawl’s flexure arm), even as the pawl is moving radially outward toward an engaged position.
  • buttresses that are able to move relative to pawls in this manner can provide that under conditions of normal use (e.g. in the absence of a fall event), a drum -mounted buttress 60 can remain positioned circumferentially rearward (i.e., in the “trailing” direction) of a pawl 20 by a relatively large distance, since the buttress will be able to move relative to the pawl to close this distance in the case of a fall event.
  • the effect of this is that the pawls, buttresses, and so on, may be designed without necessarily requiring extremely tight tolerances between the pawls and the buttresses under conditions of normal use.
  • a centrifugal gap may have a maximum dimension (measured along a circumferential path at the point of closest approach between a pawl and a buttress, with these items in their disengaged positions) of at most 10, 8, 6, 4, or 2 mm. In further embodiments, such a centrifugal gap may have a minimum dimension of at least 1, 3, 5, or 7 mm.
  • centrifugal gap will typically exhibit its maximum value when pawl-support plate 40 is in its previously-described “home” position relative to dram 80. Movement of pawl-support plate 40 along its arc of partial rotation away from this home position will cause the centrifugal gap to be reduced as described above. (Figs. 15 and 16 both depict apparatus in which the pawl-support plate 40 is in its home position.) In various embodiments, this rotational movement of plate 40 may reduce the circumferential gap by a factor of at least 10, 20, 30, 40, 50, 60, 70, 80, or 90 %. The reduction factor will be assessed using the original, maximal value of the gap.
  • the reduction factor will be (4- 1 )/4 or 75 %.
  • the circumferential relative motion that is permitted between the buttresses and the pawls can allow that, when the pawl does engage a ratchet tooth, any remaining circumferential gap can be closed by this relative motion of buttress and pawl (e.g., without the flexure arm of the pawl being subjected to large forces).
  • At least a portion of a circumferential gap between a pawl -support-plate-mounted pawl and a drum -mounted buttress may be closed by deceleration of the pawl-support plate relative to the dram, rather than by acceleration of the dram relative to the pawl-support plate.
  • the circumferential relative motion that is permitted between the buttresses and the pawls may advantageously enhance the ability of the pawls and buttresses to be separated from each other (and for the pawl to be disengaged from a ratchet tooth) at the conclusion of a “lock-up” test of the type described earlier herein.
  • a dmm sidewall 87 that bears one or more buttresses 60 thereon can be of any suitable design and can be arranged in any suitable manner.
  • a “sidewall” 87 does not necessarily have to define, or exhibit, an axially-inward surface that defines an axial boundary of space 88 into which a safety cable is wound.
  • a sidewall 87 may be a separately-made item that is e.g. attached (e.g. bolted, screwed, etc.) to a flange of a two-flanged dmm of the general type exemplified by dmm 80 of Fig. 2.
  • a flange of the dmm may provide the axially-inward surface that defines space 88; however, an entity that comprises one or more buttresses and is attached to such a flange (or, is keyed to a common shaft so as to exhibit a fixed relationship to the dmm, even if not directly attached to a flange of the dmm) so that the entity is fixed to the drum as a whole, will be considered to be a “sidewall” as used herein.
  • a buttress 60 may be located on a pawl-support plate 40 or a dmm sidewall 87. Either configuration may be preferable under various circumstances.
  • a hybrid arrangement may be used with at least one buttress being on a pawl-support plate and with at least one buttress being on a dmm sidewall.
  • a “primary” buttress may be on a dmm sidewall and a “secondary” buttress may be on a pawl-support plate (or vice-versa).
  • any such buttresses may be positioned on a pawl -support plate and/or on a dmm sidewall, when used with either of the previously-discussed forwardly- wrapped or rearwardly-wrapped pawl and flexure arm configurations.
  • pawls 20, as well as flexure arms 30, flexure-arm anchors 50, and pawl-support module 51 are positioned axially outwardly from pawl -support plate 40.
  • pawls 20 and associated arms 30, anchors 50, and module 51 are positioned further away from dmm 80 than is pawl-support plate 40, along the axial direction of the apparatus.
  • pawls 20 etc. are axially “sandwiched” between pawl-support plate 40 and sidewall 87 of dmm 80 (noting that in Fig. 15, pawl-support plate 40 is omitted so that other items can be seen).
  • Such a design may facilitate the use of buttresses 60 that are located on a dmm sidewall 87 rather than on a pawl-support plate 40 (however, such a design is not the only way that an apparatus can be configured to allow buttresses 60 to be located on a dmm sidewall 87 rather than on a pawl-support plate 40, as discussed later with regard to Figs. 16 and 17).
  • a pawl-support plate 40 as depicted in Figs. 14 and 15 will function in substantially similar manner as discussed previously herein.
  • the rotational inertia of support plate 40 (which will include contributions from pawl-support module 51, flexure arms 30 and pawls 20) will, upon rapidly-increasing rotation of drum 80, provoke the previously-described rotational “lagging” that causes bollards 84 to move relative to support plate 40 and pawls 20 (with openings, e.g. elongated slots 43, being provided in plate 40 to allow this) thus causing the previously-described camming action.
  • FIG. 14 additional openings 48 (that do not receive a bollard 84) in pawl-support plate 40 are visible; such features can be included e.g. in order to tailor the rotational inertia of support plate 40 as desired. It will be appreciated that any such features (whether through-openings or dead-end cavities, and of any suitable shape, aspect ratio, etc.), as well as other design parameters (e.g. the average and/or local thickness of support plate 40) can be manipulated in order to achieve the desired rotational inertia.
  • the rotational inertia being affected by mass in combination with distance from the axis of rotation, the overall mass of support plate 40 and associated items, and/or the spatial distribution of such mass, can be configured to provide the desired performance.
  • a pawl-support plate may be configured to have as much mass as far from the axis of rotation as possible, in order to obtain the highest rotational inertia for the minimum total mass.
  • a significant amount of the mass of a pawl support plate may be located e.g. along the radially outer perimeter of the pawl-support plate.
  • camming bollards 84 are in the form of members (e.g., metal members with a small-diameter end configured to fit into an aperture 93 of drum sidewall 87 and with an opposing, large -diameter end) with a bushing 92 mounted thereon.
  • a sidewall of such a bushing 92 can provide the contact surface 85 of bollard 84 that impinges on a contact surface 27 of a pawl 20, and/or a surface of a flexure arm 30, to cause the camming action.
  • Such a bushing may be made of, e.g., a low-friction material such as poly(oxymethylene) (e.g. DELRIN) or the like.
  • a previously-discussed sleeve bearing 70 may be made of a low-friction material; or, the bearing may be e.g. a roller bearing.
  • pawls 20 may be positioned between major surface 41 of pawl-support plate 40 and major surface 83 of drum sidewall 87 so that pawls 20 have little or no contact with these surfaces.
  • such surfaces (and/or the surfaces of pawls that face them) may comprise low-friction materials (e.g.
  • pawls 20, flexure arms 30, and/or pawl-support module 51 of amorphous metals as mentioned earlier herein may be beneficial in that such materials may exhibit low friction and high resistance to galling.
  • FIGs. 16 and 17 are partial sectional cutaway views with an axially outer portion of housing piece 112 omitted so that pawls 20 and so on can be seen; in actuality, housing piece 112 may look very similar to piece 112 as shown in Fig. 2.
  • buttresses 60 are located on (e.g., are integral extensions of) drum sidewall 87, in generally similar manner as in Figs. 14 and 15.
  • pawls 20, flexure arms 30 and pawl-support module 51 are not axially inward of pawl-support plate 40 as in the design of Figs. 14 and 15. Rather, in the design of Figs. 16 and 17 the pawls, flexure arms and pawl-support module 51 are axially outward of pawl-support plate 40, in generally similar manner to the previously-discussed designs shown in Figs. 2-3 and 8-10.
  • the axial “height” of buttresses 60 can be greater than the axial “thickness” of support plate 40 so that buttresses 60 extend axially past support plate 40 far enough to allow pawls 20 to interact with buttresses 60 in the manner previously described.
  • the outer diameter of pawl-support plate 40 can be smaller than the inner diameter defined by the radially- inward surfaces of buttresses 60. This allows pawl-support plate 40 to fit within an axially-outwardly-open- ended receptacle 96 of drum sidewall 87 as indicated in Fig. 17, with portions of the radially outward perimeter of plate 40 being concentrically bounded by buttresses 60.
  • drum sidewall 87 may comprise an axially-extending circumferential collar 97 that further establishes receptacle 96 (e.g. so that the entire perimeter of plate 40 is circumferentially bounded by portions of sidewall 87).
  • Such arrangements can allow the previously-described velocity-actuation and/or acceleration- actuation (e.g., the camming action as described earlier herein) to occur, with apawl 20 being able to move outward to an engaged position and encounter a tooth 91 of a ratchet 90, to then be jammed against a buttress 60, and so on, so as to achieve the desired rotationally-activated braking.
  • Many components and features of the apparatus of Figs. 16 and 17 are similar in function (although differing e.g. in size, shape, etc.) to the similarly-numbered items described previously herein, and will not be discussed in detail at this point.
  • a ratchet 90 takes the form of a set of teeth 91 that are integrally molded into housing piece 112 (in contrast to e.g. a separately-made ratchet ring of the type shown in Fig. 13).
  • bollards 84 (which, in this design, do not having bushings) each comprise an end that resides in an aperture 93 of drum sidewall 87 so that bollards 84 are fixed in place relative to drum 80.
  • the “slots” 43 that allow bollards 84 to move circumferentially relative to pawl-support plate 40 are in the form of radially- outwardly-open-ended “notches” rather than as orifices that are bounded on all sides by portions of pawl- support plate 40.
  • the pawls 20 (which may be made of any suitable metal, e g . steel) are made separately from pawl-support module 51 and flexure arms 30 (which may be e.g. molded of any suitable material, e.g. an amorphous metal or an engineering thermoplastic).
  • a buttress 60 may be positioned on (e.g., may be affixed to, may be an integral part of, etc.) a pawl-support plate 40 or a drum sidewall 87.
  • pawls 20, flexure arms 30, and flexure arm anchors 50 (as well as a pawl-support module 51 that integrally includes anchors 50, if such a module is present) may be positioned outward of the pawl- support plate 40 that supports them, or may be positioned axially inward of the pawl-support plate 40 that supports them. Any combination of these choices may be used and is within the scope of the disclosures herein.
  • the fall-protection apparatus is a self-retracting lifeline which meets the requirements of ANSI Z359.14-2014.
  • the arrangements disclosed herein may be used in any fall-protection apparatus in which there is a desire to enhance the performance of the product, e.g. by minimizing the occurrence of nuisance lockups that may occur during movements about the workplace, while ensuring that the braking device responds as quickly as possible in the event of an actual fall.
  • a fall-protection apparatus as described herein may comprise a housing, drum, rotationally- activated braking device, etc., of any desired size.
  • the apparatus may be sized so that it can serve as a so-called “personal” self-retracting lifeline as discussed later herein.
  • the size of the rotationally-activated braking device may be characterized e.g. in terms of the diameter of the orbital pathway 25 that is followed by pawl(s) 20.
  • the diameter of orbital path 25 may be at least 20, 30, 40, or 50 mm; in further embodiments, the diameter of orbital path 25 may be at most 150, 120, 90, or 60 mm.
  • a fall-protection apparatus as described herein may be used in concert with, or as part of, any suitable fall-protection system such as e.g. a horizontal lifeline or retractable horizontal lifeline, a positioning lanyard, a shock-absorbing lanyard, a rope adjuster or rope grab, a vertical safety system (such as e.g. a flexible cable, rigid rail, climb assist, or fixed ladder safety system), a confined- space rescue system or hoist system, and so on.
  • a fall-protection apparatus as disclosed herein may comprise a housing configured so that the interior of the apparatus is at least partially sealed (such as in the product line available from 3M Fall Protection under the trade designation (SEALED- BLOK) e.g.
  • a fall-protection apparatus as disclosed herein may be suited for use in so-called “leading edge” workplace environments.
  • the discussions herein have primarily concerned apparatus (e.g. self-retracting lifelines) that comprise a housing that is e.g. mounted to an overhead anchorage and that comprises a safety line with a distal end that can be attached to a harness of a human user.
  • apparatus e.g. self-retracting lifelines
  • Such apparatus are exemplified by the product line available from 3M Fall Protection under the trade designations TALON and NANO.
  • any such fall-protection apparatus may include, or be used with, various ancillary items which are not described in detail herein.
  • Such items may include, but are not limited to, one or more of lanyards, shock absorbers, tear strips, harnesses, belts, straps, paddings, tool holsters or pouches, impact indicators, carabiners, D-rings, anchorage connectors, and the like.
  • Many such apparatus, products, and components are described in detail e.g. in the 3M DBI-SALA Full-Line Catalog (Fall 2016).
  • the safety line of the apparatus may comprise an in-line shock absorber e.g.
  • a fall-protection apparatus that is “non- motorized” as defined and described earlier herein, may still include such items as one or more electrically- powered sensors, monitors, communication units, actuators, and the like.
  • a fall-protection apparatus as described herein may serve merely to slow the fall of a user, and/or to allow the user to descend at a controlled rate.

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  • General Health & Medical Sciences (AREA)
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Abstract

La présente invention concerne un appareil de protection contre les chutes comprenant un dispositif de freinage actionné en rotation qui comprend au moins un cliquet porté en flexion et au moins un contrefort qui se trouve sur une paroi latérale d'un tambour rotatif du dispositif de freinage.
EP21838098.8A 2020-07-10 2021-07-09 Appareil de protection contre les chutes avec dispositif de freinage comprenant un cliquet porté en flexion et un contrefort monté sur tambour Pending EP4178683A4 (fr)

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US202063050201P 2020-07-10 2020-07-10
US202163195389P 2021-06-01 2021-06-01
US202163195414P 2021-06-01 2021-06-01
PCT/IB2021/056197 WO2022009175A1 (fr) 2020-07-10 2021-07-09 Appareil de protection contre les chutes avec dispositif de freinage comprenant un cliquet porté en flexion et un contrefort monté sur tambour

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EP4178683A1 true EP4178683A1 (fr) 2023-05-17
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US20230310910A1 (en) * 2022-03-31 2023-10-05 Msa Technology, Llc Systems and Methods for Providing a Consolidated PFL or SRL Drum

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EP4178683A4 (fr) 2024-04-17
US11779784B2 (en) 2023-10-10
TW202210125A (zh) 2022-03-16
WO2022009175A1 (fr) 2022-01-13
US20230228305A1 (en) 2023-07-20

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